The Waters of Centaurus(1970)
(The second book in the Sibyl Blue series)
A novel by Rosel George Brown
In the wilderness of comparatively new planets there's nothing quite as effective as a civilized front. With a bag-full of demure deceptions--green face cosmetics, rouged knees and her purple petal-textured Botticelli--Sybil Sue Blue, police sergeant, fights against the alien forces that threaten the security of our galaxy. Sybil Sue Blue is a master at attracting difficult situations leading into tight corners that would daunt a lesser woman. Although Earth has had diplomatic relations with Centaurus for quite some time, there's still quite a bit of undiscovered territory..and some attractive unknown elements. The Krilanrians, for instance, and particularly their leader Gide Girais, the Sea King. Sybil Sue Blue, tough, beautiful, gin-slinging femme fatale has a ball tracking him down. Just because Gide is the enemy and a fish-like alien to boot doesn't blind her natural reaction to the fact that he's extremely attractive.
Used availability for Rosel George Brown's The Waters of Centaurus